1. Field of the Invention
This invention relates to an imaging apparatus for use in an electronic imaging camera and includes a charge transfer device such as charge coupled device (CCD) or the like. The invention is concerned more particularly with imaging apparatus which produce an electric signal representation of an image received by the camera. The electrical signal representation can be processed to provide a video output.
2. Prior Art
Of interest as pertinent general prior art are a number of U.S. Letters Patent identified as follows:
______________________________________ U.S. Pat. No. Inventor(s) Issue Date ______________________________________ 3,585,439 Robert J. Schneeberg June 15, 1971 3,922,576 Charles M. Redman November 25, 1975 3,958,079 Arthur L. Case et al. May 18, 1976 4,015,115 Donald G. Corcoran March 29, 1977, and 4,178,528 Andrew J. Kennedy December 11, 1979. ______________________________________
It is known from U.S. Pat. No. 4,253,120 to Peter A. Levine issued Feb. 24, 1981 and entitled "Defect Detection Means for Charge Transfer Imagers" to position a charge coupled device (CCD) in the optical path of a low resolving power imaging optics which project an image on a light responsive surface of the CCD. The CCD is operatively associated with a source of clock voltages and responds to clock pulses therefrom to effect delivery of a serial picture sample output corresponding to the image projected on the surface of the CCD. The serial picture sample output is processed electronically by a signal processor to derive a video output. The imager as disclosed is of the frame or field type; CCD imagers of this type are known, for example, from U.S. Pat. No. 4,032,976 to Peter A. Levine, issued June 28, 1977 and entitled "Smear Reduction in CCD Imagers" which discloses in detail a CCD Imager including storage registers which can be associated with a clock voltages source suitable for reading out signals stored in the imager.
It is known from U.S. Pat. No. 4,338,627 to John J. Stapleton, issued July 6, 1982 and entitled "LED/CCD Multiplexer and Infrared Image Converter" to utilize a CCD sensor to develop a stored charge image of signals coupled to the CCD sensor from a light-emitting diode (LED) array, the signals from the array being coupled to the CCD via a bundle of optical fibers. At predetermined intervals, for example every six microseconds, the stored charges are shifted out of the CCD sensor and subsequently amplified and used for image reconstruction.
In recent years, microchannel electron multipliers have become known, the multipliers include microchannel plates to effect electron multiplying, these microchannel multipliers being particularly useful in image amplifiers. The microchannel plates are characterized by high electron gain, low noise, high spatial resolution, high speed, small weight and relatively low power consumption. As used in image intensifiers, the microchannel plate is usually associated with a photocathode upon which an optical image or the like to be intensified is projected. Electrons produced by the photocathode are used as input electrons to individual ones of the channels in the microchannel plate, these electrons in each individual multiplier channel are in effect amplified by generation of secondary electrons, the electron output from the plate being projected on a phosphor screen or the like to enable a user to view an intensity enhanced version of the image which was initially projected on the photocathode. An exemplary camera tube, utilizing a microchannel plate, is disclosed in the U.S. Pat. No. 4,120,002 to Albert J. Lieber issued Oct. 10, 1978 and entitled "Streak Camera Tube", the microchannel plate being associated with a photocathode and a phosphor screen. The screen is coupled to a fiber optic plate.
It is known from the U.S. Pat. No. 4,237,488 to Yasuo Takemura, granted Dec. 2, 1980 and entitled "Blemish Compensating System for a Solid State Image Pick-Up Device" to provide a solid state image pick-up device in the form of pick-up elements arranged to store electrical charges corresponding to an optical image formed on the light sensitive portions thereof, the pick-up elements being formed as part of a CCD pick-up device. Electronic circuitry is provided to energize a drive circuit which causes the CCD device to produce electrical signals corresponding to an optical image received via a color strip filter.
It has long been known from U.S. Pat. No. 3,688,143 to Albert Lieb et al., granted Aug. 29, 1972 and entitled "Multi-Diode Camera Tube with Fiber-Optics Faceplate and Channel Multiplier" to provide a camera tube which includes a microchannel plate used as an image intensifier in front of a photodiode array. Image light incident to the photocathode surface is converted into electrons, which are subsequently amplified by the microchannels of the plate. The output side of the microchannel plate is, as is conventional, a phosphor screen which converts the electrons produced in the microchannels back to visible light which is thereafter detected by a multidiode disk.
The camera tube of Lieb et al., supra, requires that electrons produced by the microchannels be converted to visible light which must be thereafter detected by the multidiode disk to produce an electrical signal output, a distinct disadvantage.